A guidewire is used for guiding a catheter to a treatment site in which it is difficult to perform a surgical operation, for example, percutaneous transluminal coronary angioplasty (PTCA). A guidewire may also be used to guide a catheter which is used for treatment that seeks to be less invasive to the human body, or a catheter used in diagnosis such as cardioangiography. The guidewire used in PTCA is inserted into the vicinity of a stenosed site of a blood vessel (i.e., a target site) together with a balloon catheter in a state in which a distal end of the guidewire is made to protrude from a distal end of the balloon catheter. The distal portion of the balloon catheter is then guided to the vicinity of the stenosed site of a blood vessel. The guidewire dilates the stenosed site of a blood vessel by passing through the stenosed site and guiding the distal portion of the balloon catheter to the stenosed site of the blood vessel.
The guidewire in the related art has a wire main body made primarily of super elastic alloy and a coil that covers a distal portion of the wire main body. For example, refer to the guidewire described in Japanese Patent Application No. 2009-202030. By providing such a configuration, it is possible to obtain sufficient flexibility in the distal portion and to reduce sliding resistance of the distal portion. It is thus possible to obtain a guidewire having excellent operability (such as blood vessel followability or blood vessel selectivity). However, several problems arise when performing the above-described treatment using this guidewire with a flexible distal portion.
A problem may arise in that it is difficult to obtain information about what degree the stenosed site of a blood vessel is stenosed (i.e., how much the stenosis is occluding the blood vessel). Specifically, an operator obtains information about the stenosed degree (i.e., degree of stenosis) by making the distal portion of the guidewire abut/contact the stenosed site of a blood vessel. If the distal end of the guidewire is flexible, however, it is difficult to obtain sufficient information (sensation or responses) to determine the stenosed degree of the stenosed site of a blood vessel even when the guidewire abuts/contacts the stenosed site of the blood vessel.
Another problem may arise in that it is difficult for the guidewire to pass through the stenosed site of a blood vessel if the distal portion of the guidewire is flexible. That is, if the distal portion of the guidewire is flexible, even if the guidewire is pushed in order to pass through the stenosed site of a blood vessel, the distal portion of the guidewire may bump into the stenosed site of a blood vessel and become curved and deformed. Therefore, it may be impossible to pass the stenosed site of a blood vessel as expected.